Print disc assembly for a printer

ABSTRACT

In a printer a print disc assembly comprises a central support wheel having a plurality of axial openings adjacent to periphery. A spoked type disc is secured to one side of the wheel and a spoked interposer to the other side. Slideable slugs in the axial openings transmit impact energy from the interposer to the type disc for printing.

United States Patent [1 1 Bolan et al.

[ Nov. 19, 1974 PRINT DISC ASSEMBLY FOR A PRINTER [75] Inventors: Peter Samuel Bolan, Vestal; Aramis Duane Bryant, Johnson City; John Edward Drejza, Endwell; Charles Stephen Holovka, Endicott; Ludwig Wilhelm Weber, Vestal, all of NY.

[73] Assignee: International Business Machines Corporation, Armonk, NY.

[22] Filed: May 21, 1973 [21] Appl. No.: 362,563

[52] US. Cl 197/53, 197/6.6, 101/936, 335/277 [51] Int. Cl B41j 1/32 [58] Field of Search 197/48-55, 197/18, 6.6, 6.7; 101/93 C, 109, 110; 335/277, 193

[56] References Cited UNITED STATES PATENTS 3,149,562 9/1964 Wilkins et al. 101/93 C X 3,282,389 11/1966 Rudisch et a1. 197/6.6 3,295,652 l/1967 Sasaki 197/53 3,371,766 3/1968 Staller 197/53 3,585,927 6/1971 Burns et a1 101/93 C 3,651,915 3/1972 Folkens 101/93 C 3,675,172 7/1972 Petusky 101/93 C X 3,698,529 10/1972 Cattaneo 197/49 3,715,978 2/1973 Raider 101/93 C 3,759,174 9/1973 Quirijnen 101/93 C Primary Examiner-Robert E. Pulfrey Assistant ExaminerE. H. Eickholt Attorney, Agent, or Firm-Francis V. Giolma [5 7] ABSTRACT In a printer a print disc assembly comprises a central support wheel having a plurality of axial openings adjacent to periphery. A spoked type disc is secured to one side of the wheel and a spoked interposer to the other side. Slideable slugs in the axial openings transmit impact energy from the interposer to the type disc for printing.

10 Claims, 7 Drawing Figures PRINT DISC ASSEMBLY FOR A PRINTER BACKGROUND OF THE INVENTION 1. Field of Invention The invention relates to printers and it has reference in particular to printers having a rotatable print wheel with flexible type character bearing fingers.

2. Description of Prior Art Printers have been known heretofore such as shown in US. Pat. No. 3,371,766 which issued on Mar. 5, 1968 to K. J. Staller, entitled Printing Apparatus, which discloses a printer having a disc with slideable guide blocks 2 having integral type characters on the front face projecting through holes in a beryllium copper spring finger 4. A print hammer 7 impacts the rear of the guide block 2 to drive the type characters into the document for printing.

Also known are printers such as disclosed in (IBM Docket EN972010) patent application Ser. No. 259,320 filed 06/2/72 of Johann H. Meier, et al, entitled Type Disc interposer Assembly for a Printer.

SUMMARY OF THE INVENTION Generally stated it is an object of the invention to provide an improved print disc assembly for a printer.

More specifically it is an object of the invention to provide an improved print disc assembly for a printer.

More specfically it is an object of the invention to provide a print disc assembly that provides improved print quality.

Another object of the invention is to provide for combining a low inertia type element wth additional operating mass so as to obtain improved print quality.

Yet another object of the invention is to provide a light weight type element with a separate operating mass for improving the operating characteristics thereof.

It is also an object of the invention to provide a low profile type element on a light weight print disc.

Another important object of the invention is to provide a light weight type element with a separate operating mass of many times the mass of the type element.

It is also an important object of the invention to provide in a print disc assembly for a printer for using a resilient interposer for impacting an operating mass and providing a substantially rigid stop for limiting bending of the interposer to an area relatively close to the end of the interposer.

Still another important object of the invention is to provide in a print disc assembly for preloading a resilient type disc and a spoked interposer with a slideable operating mass therebetween.

Yet another important object of the invention is to provide for interposing a resilient damper ring between a spoked interposer and a plurality of slideable operating slugs used to impact the type against the document.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawing.

DESCRIPTION OF THE DRAWING In the drawing FIG. 1 is a schematic isometric view in part of a printer mechanism embodying the invention in one of its forms.

FIG. 2 is an enlarged cross-sectional view along the line 2-2 of FIG. 1.

FIG. 2a is a partial front elevational view of the type disc and securing means.

FIG. 3 is a partial view in the side elevation of a portion of a print disc and type element of the prior art.

FIG. 4 is a partial view in the side elevation of a portion of a type disc assembly embodying the present invention with the center line of the slug coinciding with the center line of the type character.

FIG. 5 is a partial view in the side elevation of a portion of a print disc assembly embodying the present invention with the center line of the slug above the middle and is at the effective center line of the type character and FIG. 6 is a partial view in the side elevation of a portion of a print disc assembly embodying the present invention wherein the center line of the slideable slug is below the middle and is at the effective center line of the type character on the type disc.

DESCRIPTION OF A PREFERRED EMBODIMENT As shown in FIG. 1 a rotatable print disc assembly 10 is positioned to move past a document 12 which is backed up by a platen 14, in conjunction with a print hammer 16 operated by a solenoid 18 to impact the print disc against the document for printing. Contact paper may be used, a type ribbon may be used or the type may be inked by any suitable means for producing an image on the document.

The print disc assembly 10 comprises a print disc 20 having radial slots 21 defining a plurality of radial spokes or fingers 22 having type characters 23 thereon for impacting the document 12. The type characters 23 may be an integral part of the fingers 22 being for example formed by etching away the material of the fingers to leave raised type characters.

Referring to FIGS. 1 and 2 it will be seen that the type disc assembly 10 comprises a central hub portion 24 having a recess 26 disposed to fit on a shoulder 28 on the end of a rotatable shaft 30. An emitter disc 32 is mounted on the shoulder portion 28 of the shaft 30 comprising a plastic disc 33 having a metal ring insert 34 provided with teeth 35 above the periphery for cooperation with a transducer (not shown) for determining the relative position of the print disc. The disc 33 is provided with a recess 36 and aprojecting circular rib 38 having an inclined surface portion 40 for a purpose to be explained hereinafter. The hub 24 is secured to the shaft 30 by means of a knurled screw 42 having a threaded portion 43 threadably engaged in an opening in the shaft 30.

The hub 24 forms a mount for a support wheel portion 46 which is provided with a plurality of axial openings about the edge of the wheel for receiving separate type operating slugs 48 which are slideably disposed in the openings 49 to engage and actuate an associated type finger 22, one such opening being associated with each type character bearing finger 22. The print disc 20 is secured to the hub 24 by means of a mumber of rivets 40 which project through the hub and are provided with grooved end portions 52 disposed to be positioned in buttonholeshaped openings 54 of the print disc for detachably securing the disc to the support wheel. Details of the mounting are shown in FIG. 2a.

The hub 24 is provided with a shoulder portion 56 for receiving an interposer disc '58 which is slotted regularly to provide a plurality of spokes or fingers 60 associated one with each of the type operating slugs 48. The support wheel 46 is provided with a circular rib 62 positioned just inside the row of holes 49. This rib 62 provides a stop or fulcrum for the interposer fingers 60 and support for a detuning ring 64 comprising a polyurethane material having a nylon fabric backing which is positioned between the interposer finger 60 and the type operating slug 48 to control the action of the hammer interposer slug and type finger system, to prevent the type finger from arriving at the platen before the slug arrives. The ring 64 is wider than the opening of the hole 49 so that it engages the rear surface of the support wheel 46 when the interposer 60 is struck by the print hammer 16 to impact and impel an associated slug 48 during printing. The rear surface of the interposer 60 is bevelled so as to provide a restoring force for the print hammer 16 as the print wheel assembly rotates.

The rivet 50 functions to loosely couple the print disc 20 with a support wheel 46 while at the same time clamping the interposer 58 to the support wheel 46 through the medium of a clamp ring 68. When the knurled screw 42 is tightened the hub 24 of the support wheel 46 is forced toward the emitter disc 33 and the inclined surface 40 of the emitter disc engages the disc 20 deforming it as shown so as to pretension the type finger 22 against the type operating slug 48 and the interposer finger 60. When an interposer finger 60 is struck by the print hammer 16, it bends about the rib 62 and impacts the slug 48 which drives the corresponding type disc finger 22 to impact its type character 23 against the document for printing.

Referring to FIG. 3 the reference numerals 22a and 23a denote a previous construction of type finger and type character bearing slug. Because the prior design had a relatively high mass type slug 23a mounted on the type finger 22d, partial printing of the character often resulted. In the case shown only the bottom of the character will print because the high inertia of the type slug prevents the type slug from rotating into position to print a full character before the complete unit bounces off the platen. With the construction in FIG. 4 the force of the slug 48 is always applied behind the center of gravity of the type 23 resulting in a good type-platen alignment (full character printing) during printing. It can be seen that the slug mass system will correct for any misalignment of the type face, not just bottom misalignment. As shown in FIGS. 5 and 6 the slug design can be varied to correct for severe variations in type character geometry. For example, in FIG. 5 the curved ends of the type actuating slug 48a are proportioned to raise the effective center line of the slug so that it is substantially in alignment with the principal portion of the type character 23b on a finger 22b. In FIG. 6 the contour of the ends of the type actuating slug 48b are varied to place the effective mass of the type actuating slug below the'normal center line so that it is substantially in alignment with the principal mass of the type character 23c on a finger 22c.

Instead of utilizing a type disc having relatively heavy type slugs secured thereon as in the prior art separate slideable type operating slugs are used to provide the stored energy mass for printing, and the type character on the print disc has a relatively low mass. For example the mass of the movable type operating slug may be 0.18 grams as compared with a mass for the type character on the type finger of 0.03 grams. The type fingers are 0.875 inches long and 0.08 inches wide, while the interposer fingers are 0.875 inches long and 0.080 inches wide. The stiffness of the interposer is much greater than the stiffness of the fingers on the type disc the interposer being for example 0.030 inches thick whereas the finger of the print disc is 0.0 l 0 inches thick making the interposer finger on the order of 27 times as stiff. The print disc is 3.448 inches in diameter; the interposer is 3.47 inches in diameter, and the rib 62 on the support wheel is 2.9 inches inside diameter and 3.02 inches outside diameter. This places the rib approximately 0.25 inches from the end of the interposer finger which is 0.875 inches long. The print disc when assembled is deformed so as to provide a prestressing of thetype fingers on the order of 20 to 40 grams force. Both the interposer 58 and the type disc 20 are provided with damping rings 19-25 and 27-29, respectively consisting of a neoprene material backed with a dacron fabric. A metal ring 31 may be secured to the outer surface of the damping ring 19 on the type disc to reinforce the type bearing fingers. The separate slug and type construction permits a curved contact surface on the slug to provide the contact between the slug and type, permitting the use of a sufficient mass for good print quality while having a sort of universal joint connection between the slug and type, adjacent the center of mass of the type which permits the relatively light mass type to align independently of the slug during printing, for the best print quality.

From the above description and the accompanying drawing it will be apparent that we have provided an improvied print wheel assembly which utilizes a low mass type character and an independent slug which provides not only the energy for printing by driving the type against the platen, but also permits relative adjustment of the type and slug to align the type for printing. The slug is driven through the action of a print hammer and an interposer with a visco-elastic ring being positioned between the interposer and the drive type slug to detune the action of the hammer, interposer slug,

fingers are designed to allow deflection both towards the platen and in a plane perpendicular to the plane of the paper without exceeding the structural limits of the material. In the slug-type design herein disclosed the force of the slug is always applied behind the center of gravity of the type, resulting in good type-platen alignment during printing.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In a print disc assembly for a printer having a movable carriage with a rotatable support shaft;

a support wheel secured to and rotatable with said shaft having a plurality of axial openings through said wheel adjacent the periphery thereof;

a resilient spoked print disc mounted on one side of and secured to said support wheel having integral type characters adjacent the ends of said spokes;

a plurality of slugs slideably disposed in said openings to engage different ones of said spokes, and

a resilient spoked interposer secured to and rotatable with said support wheel on the other side with the spokes of said interposer normally biasing said slugs against the corresponding spokes of said print disc.

2. The invention as defined in claim 1 characterized by said support wheel having integral hub portions on opposite sides to receive said print disc and said interposer.

3. The invention as defined in claim 2 characterized by said support wheel having a shoulder concentric with said wheel on the interposer side engaging said interposer spokes at less than one fifth the distance from the periphery of said interposer to the center.

4. The invention as defined in claim 3 characterized by a resilient detuning ring loosely mounted on said shoulder said support wheel between said slugs and said interposer spokes.

5. The invention as defined in claim 4 characterized by said type disc being detachably secured to said support wheel.

6. The invention as defined in claim 5 characterized by said print disc having a damper ring secured thereto intermediate said type characters and the center of said type disc.

7. The invention as defined in claim 6 characterized by metal ring secured to said damper ring.

8. The invention as defined in claim 4 characterized by said detuning ring acting as a stop between said interposer and said support wheel to limit movement of said interposer spokes and minimize nipping between an impacting print hammer and an adjacent interposer spoke.

9. The invention as defined in claim 1 characterized by said shaft having a shoulder portion with an inclined surface engaging the type character side of said print disc and having means to bias said print disc assembly against said inclined surface to prestress said spokes of said print disc.

10. The invention as defined in claim 1 characterized by said slugs being contoured to provide different centers of mass in accordance with the effective centers of the associated type characters. 

1. In a print disc assembly for a printer having a movable carriage with a rotatable support shaft; a support wheel secured to and rotatable with said shaft having a plurality of axial openings through said wheel adjacent the periphery thereof; a resilient spoked print disc mounted on one side of and secured to said support wheel having integral type characters adjacent the ends of said spokes; a plurality of slugs slideably disposed in said openings to engage different ones of said spokes, and a resilient spoked interposer secured to and rotatable with said support wheel on the other side with the spokes of said interposer normally biasing said slugs against the corresponding spokes of said print disc.
 2. The invention as defined in claim 1 characterized by said support wheel having integral hub portions on opposite sides to receive said print disc and said interposer.
 3. The invention as defined in claim 2 characterized by said support wheel having a shoulder concentric with said wheel on the interposer side engaging said interposer spokes at less than one fifth the distance from the periphery of said interposer to the center.
 4. The invention as defined in claim 3 characterized by a resilient detuning ring loosely mouNted on said shoulder said support wheel between said slugs and said interposer spokes.
 5. The invention as defined in claim 4 characterized by said type disc being detachably secured to said support wheel.
 6. The invention as defined in claim 5 characterized by said print disc having a damper ring secured thereto intermediate said type characters and the center of said type disc.
 7. The invention as defined in claim 6 characterized by metal ring secured to said damper ring.
 8. The invention as defined in claim 4 characterized by said detuning ring acting as a stop between said interposer and said support wheel to limit movement of said interposer spokes and minimize nipping between an impacting print hammer and an adjacent interposer spoke.
 9. The invention as defined in claim 1 characterized by said shaft having a shoulder portion with an inclined surface engaging the type character side of said print disc and having means to bias said print disc assembly against said inclined surface to prestress said spokes of said print disc.
 10. The invention as defined in claim 1 characterized by said slugs being contoured to provide different centers of mass in accordance with the effective centers of the associated type characters. 